Communication through the use of wireless communication systems has achieved wide popularity in recent years. Multi-user, wireless communication systems with increased capacity and performance have been implemented as a result of advancements in digital communication technologies. These communication services have become affordable, further increasing their popularity.
In a wireless communication system, a radio communication channel extends between a sending station and a receiving station. The radio channel is defined upon a portion of the electromagnetic spectrum. This communication link between the sending and receiving stations is wireless and does not require a wire line connection. Communication can thereby be untethered.
A cellular communication system is exemplary of a wireless, multi-user radio communication system. Here, several fixed-site base stations are installed to cover a geographical area. By transmitting signals with controlled power, the same frequencies can be re-used at different locations throughout the geographical area. Thereby, communications capacity is maximized. Power control is at the core of cellular system design.
Various standards have been developed for cellular communication systems. Interim standards IS-95 and IS-98, promulgated by the EIA/TIA, are cellular communication standards which rely on CDMA (code division multiple access) communication techniques. In a CDMA communication system, several communication signals share a common frequency channel. In such a communication scheme, the power levels of each user must be regulated to achieve optimal capacity. Power control is needed to ensure that none of the signals overwhelm the other signals.
These interim standards set forth requirements for closed-loop power control. In an exemplary closed-loop power control scheme, power control information is generated and transmitted by the network infrastructure to a mobile handset. The control information is sent in the form of power control bits. When received at the mobile handset, the control bits adjust the level of transmitted power.
The closed loop power control scheme augments open loop power control methods. These schemes use approximation techniques based on the assumption that both the downlink and uplink channels experience similar path losses. Open loop power control schemes are generally slower and less accurate than closed loop power control schemes. Closed loop power control schemes are typically more complex, but, necessary to ensure that the transmitted signals are in compliance with the requirements set forth in the aforementioned standards. Interim standards IS-95 and IS-98 utilize a 800 Hz power control loop. Future standards will exploit faster power control schemes. Future standards will also occupy a wider bandwidth and require finer power control.
Improvements in digital communication techniques permit high-speed data and faster, finer power control. However, conventional closed-loop gain control circuitry is limited in speed and accuracy. As power control times decrease, conventional techniques will become inadequate.
A manner by which to provide for faster closed-loop gain control would be advantageous.
It is in light of this background information related to gain control in a wireless communication system that the significant improvements of the present invention have evolved.